Actors and directors speak frequently of improvising on film sets, but would you believe that some of cinema’s most iconic lines were off the cuff and not from a script?

Robert DeNiro’s ‘You talkin’ to me?’  in ‘Taxi Driver’? Improvised. Humphrey Bogart’s ‘Here’s looking at you, kid’ in ‘Casablanca’? Improvised, too. Get the stories behind those and a couple dozen other classic films that benefitted from spontaneous moments of movie magic.

Be sure to leave the annotations on the YouTube player, as they explain just what elements were improvised in each of the scenes.

Some language is NSFW.

[via BlackBook]